Polyvinylbutyral interlayer sheet with improved adhesion to glass and a process for preparing same

ABSTRACT

The present invention is an improved PVB composition comprising an adhesion control agent which is a mixture of potassium and magnesium salts in a ratio of from about 0.05:1 to about 5:1, by weight, potassium salts to magnesium salts. The present invention also describes a method for improved control of adhesion of PVB to glass.

This application is a divisional of U.S. patent application Ser. No.10/519,670, filed Dec. 27, 2004 (pending), which is incorporated hereinby reference, which is a 371 of international application PCT/US03/23817filed Jul. 29, 2003, which claims the benefit of U.S. ProvisionalApplication No. 60/400,231, filed Jul. 31, 2002.

BACKGROUND OF THE INVENTION

Plasticized polyvinyl butyral (PVB) sheet is used in the manufacture oflaminate structures such as, for example: windshields for vehiclesincluding automobiles, motorcycles, boats and airplanes; homes andbuildings; shelving in cabinets and display cases; and other articleswhere structural strength is desirable in a glass sheet.

Laminated safety glass comprises a sandwich of polyvinyl acetalsheeting, typically polyvinyl butyral sheeting, between sheets (lites)of glass. These laminated glass composites are required to perform tostringent requirements including good impact performance,weatherability, and transparency.

A recent design trend toward the use of laminated safety glass in openedge windshield applications and in automobile sidelites hasnecessitated the need for laminated glass with improved adhesionrobustness. In these open edge applications, the edge of the windshieldis not encased with a gasket, but is exposed to the environment.Exposure of a PVB interlayer to the environment can result in moisturebeing absorbed into the interlayer. Moisture absorbed into theinterlayer can affect the adhesion of the interlayer to the glass, andthereby cause defects in the laminate.

Japanese Kokai Publication Hei 7-172878 describes an interlayer withalternating sheets of specialized PVB constructed in order to improvethe moisture robustness of the laminate. Japanese Kokai Publication60-210551 describes the use of silicon oils in PVB sheeting, andJapanese Kokai Publication Hei 7[1995]-237943 describes the use oforganic acids in PVB sheeting to improve moisture robustness.

The use of magnesium alone as an adhesion control agent is well known.For example, WO 9961243 describes the use of magnesium salts alone asadhesion control agents. However, one problem with using magnesium aloneas an adhesion control agent is that it can yield asymmetric adhesiondepending upon the structure of the glass laminate. U.S. Pat. No.6,383,647 describes adhesion control agents. U.S. Pat. No. 4,292,372describe the use of potassium and magnesium salts as adhesion controlagents for PVB. U.S. Pat. No. 3,249,490 and U.S. Pat. No. 3,249,489describe the use of mixtures of alkali and alkaline earth metal salts asadhesion control agents. However, the Applicant has discovered that theratio of potassium ions to magnesium ions present in a PVB compositionis an important parameter for improving adhesion robustness in a PVBlaminate. The importance of the ratio of potassium ions to magnesiumions and the effect of the ratio of said salts on adhesion robustness ina PVB laminate has not been fully appreciated or described in the art.

It would be desirable to have improved control over adhesion robustnessof PVB to glass in a laminate by controlling the ratio of potassium ionsto magnesium ions.

SUMMARY OF THE INVENTION

In one aspect, the present invention is a method for controllingadhesion of PVB to glass in a glass/PVB laminate comprising the step:mixing an adhesion control agent with PVB and a plasticizer to obtain aplasticized PVB composition, wherein the adhesion control agentcomprises a mixture of potassium and magnesium salts in a ratio that isin the range of from about 0.05:1 to about 5:1 (weight:weight, potassiumions:magnesium ions) and wherein the salts are included in aconcentration of up to about 1000 ppm based on the total weight of theplasticized PVB composition.

Preferably the ratio is about 1:1 to about 5:1, more preferably theratio is about 2:1 to about 5:1, even more preferably the ratio is about3:1 to about 5:1, and most preferably the ratio is about 4:1 to about5:1.

The salts are preferably included in a total concentration of from about200 to about 1000 ppm, more preferably about 250 to about 900 ppm, andmost preferably about 300 to about 800 ppm.

In another aspect, the present invention is a plasticizedpolyvinylbutyral (PVB) composition having from about 17 wt % to about 23wt % residual hydroxyl, plasticizer in an amount of from about 30 toabout 50 parts per hundred (pph) PVB, and an adhesion control agentcomprising a mixture of potassium and magnesium salts in a ratio that isin a range of from about 0.05:1 to about 5:1 (weight:weight, potassiumions:magnesium ions) and wherein the salts are included in a totalconcentration of up to about 1000 ppm.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment, the present invention is a plasticized PVBcomposition comprising an adhesion control package that is a mixture ofpotassium and magnesium salts. The adhesion control package is a mixtureof salts combined in a weight ratio of from about 0.05:1 to about 5:1(weight potassium ions:weight magnesium ions). Below a ratio of 0.05:1 alaminate may exhibit asymmetric adhesion, depending on the constructionof the glass. Above a ratio of 5:1 the laminate may exhibit low adhesionalong the edge of a laminate wherein moisture has been absorbed alongthe periphery, as measured by the edge pummel test. Preferably the saltsare added in a ratio in the range of from about 1:1 to about 5:1, morepreferably the salts are mixed in a ratio in the range of from about1.5:1 to about 4.5:1, even more preferably the salts are added in aratio in the range of from about 2:1 to about 4:1. Most preferably thesalts are added in a ration in the range of from about 3:1 to about 4:1.

Salts of the present invention can be potassium or magnesium salts ofvarious counterions. Potassium and/or magnesium salts suitable for usein the practice of the present invention can be potassium or magnesiumsalts formed in combination with either organic or inorganic anioniccounterions. Salts of organic acids having from 2 to 22 carbon atoms canbe preferable. For example, preferred for use in the practice of thepresent invention are carboxylate salts obtained from acids selectedfrom the group consisting of: acetic; formic; citric; stearic; 2-ethylhexanoic, 2-ethyl butyric, heptanoic, propanoic, pentanoic, hexanoic,heptanoic, lauric, and the like.

The adhesion control salt mixture can be included in some finite amount,but less than 1000 parts per million (ppm) based on the total weight ofthe PVB composition. In the practice of the present invention when thesalt concentration is above about 1000 ppm total salt, the adhesion ofthe PVB to glass can be at an undesirable level—generally lower thandesired.

One method for measuring adhesion robustness is the so-called “edgepummel test”. A laminate is considered to have a good edge pummelresult, and thus acceptable adhesion robustness, if after testing, thelaminate has a uniform pummel value across the laminate, that is, nobare vinyl along the edges. A passing result is one wherein the pummelvalue decreases by not more than 2 units from the center of the laminate(center) to the edge of the laminate (edge). Preferable performance isnot more than a 1 pummel unit difference from the center to the edge andmost preferably, there is no difference in the pummel measurementsbetween the center and edge.

Another method of measuring adhesion is compressive shear test. Asdetermined by the compressive shear test, adhesion of a laminate of thepresent invention is within the range of from about 965 to about 1800N/cm² (1400-2600 psi). Preferably adhesion is in the range of from about1000 N/cm² to about 1775 N/cm², more preferably from about 1200 N/cm² toabout 1750 N/cm². Most preferably adhesion is from about 1240 N/cm² toabout 1730 N/cm².

PVB of the present invention can have from about 30 to about 50 partsper hundred (pph) of a plasticizer, based upon the total dry weight ofthe resin. Plasticizer can be added in any compatible amount desirableto obtain a plasticized PVB sheet. Preferably, the present invention canhave from about 30 to about 45 pph of plasticizer, more preferably fromabout 30 to about 40 pph plasticizer, and most preferably from about 32to about 45 pph plasticizer. The “dry weight” as used herein refers tothe weight of the dry resin, that is, after water has been removed fromthe resin.

Plasticizers of the present invention can be chosen from any that areknown or used conventionally in the manufacture of plasticized PVBsheeting compositions. Preferred plasticizers for use herein arediesters obtained by the reaction of triethylene glycol or tetraethyleneglycol with aliphatic carboxylic acids-having from 6 to 10 carbon atoms;and diesters obtained from the reaction of sebacic acid with aliphaticalcohols having from 1 to 18 carbon atoms. More preferably theplasticizer is either tetraethylene glycol di(2-heptanoate) (4G7),triethylene glycol di(2-ethylhexanoate) (3GO) or dibutyl sebacate (DBS).Most preferably the plasticizer is 3GO.

The PVB composition of the present invention has from about 17% to about23 wt % residual hydroxyl. Preferably, the hydroxyl content is fromabout 18 to about 21%, more preferably from about 18 to about 20.5%, andmost preferably from about 18.5% to about 19.5%. The hydroxyl value canaffect the compatibility of the plasticizer in the PVB, as well as otherproperties of the PVB. Generally, and without being held to the absoluteaccuracy of the following statement, the lower the hydroxyl content, themore compatible the plasticizers preferred for use in the practice ofthe present invention.

The present invention can require the use of a surfactant. Surfactantssuitable for use herein include: sodium lauryl sulfate; ammonium laurylsulfate; sodium dioctyl sulfosuccinate; ammonium perfluorocarboxylateshaving from 6 to 12 carbon atoms; sodium aryl sulfonates, adducts ofchlorinated cyclopentadiene and maleic anhydride; partially neutralizedpolymethacrylic acid; alkylaryl sulfonates; sodium N-oleyl-N-methyltaurate; sodium alkylaryl polyether sulfonates; triethanolamine laurylsulfate; diethyl dicyclohexyl ammonium lauryl sulfate; sodiumsecondary-alkyl sulfates; sulfated fatty acid esters; sulfated arylalcohols; and the like. Preferable surfactants include sodium laurylsulfate, sodium dioctyl sulfosuccinate, sodium cocomethyl tauride, anddecyl(sulfophenoxy)benzenesulfonic acid disodium salt. Most preferableis sodium dioctyl sulfosuccinate (DOSS).

The surfactant can be included in any effective amount for theparticular set of process conditions practiced. The Applicants havefound that an effective amount is at least 0.1 parts per hundred (pph)by weight, based on the weight of PVA. For example, the surfactant canbe included in an amount of from about 0.10 to about 0.70 pph by weight.

Optional additives can be included in a resin composition of the presentinvention. Such additives include, for example, antioxidants, lightstabilizers, and/or surface tension controlling agents.

U.S. Pat. No. 3,153,009, for example, describes a process formanufacturing PVB suitable for use in the practice of the presentinvention, and is incorporated herein by reference. PVB resins suitablefor the practice of the present invention can be prepared by mixingpolyvinyl alcohol (PVA) with butyraldehyde in an aqueous medium in thepresence of an acid or mixture of acids, at a temperature of from about5° C. to about 100° C.

A PVB sheet can be obtained from PVB resin described herein by either anextrusion process or by a co-extrusion process, as is conventionallyknown in the art. For example, a PVB sheet can be obtained from the PVBresin of the present invention by co-extruding the resin, plasticizer,and/or other optional additives at a temperature of from about 175° C.to about 225° C.

EXAMPLES

The following Examples and comparative examples are presented to furtherillustrate the present invention. The Examples are not intended to limitthe scope of the invention in any manner, nor should they be used todefine the claims or specification in any manner that is inconsistentwith the invention as claimed and/or as described herein.

The following tests were used in the examples and comparative examplesbelow.

Edge Pummel (Moisture Resistance) Test: A laminate is placed in a hot,humid environment (95% RH, 50° C.) for 2 weeks. After the 2 week period,the laminate is conditioned to −18° C. for a minimum of 3 hours. Thechilled laminate is held at a 45° angle on a metal plate and struck witha 227 g (0.5 lb) hammer until the glass was broken. The amount of barePVB at the edges was measured (in mm) and is reported as the laminate'sedge pummel.

Compressive Shear Adhesion Test: The compressive shear strength isdetermined by sawing a laminate into six 2.54 cm×2.54 cm chips. Thechips are held in a jig at 45° and a compression testing instrument isused to place force on the chip at the rate of 0.25 cm/min. The amountof force to cause cohesive failure of the glass-PVB bond is thecompressive shear strength of the laminate.

Hydroxyl number is determined according to procedures described in ASTMD 1396-92.

PVB resin containing a residual hydroxyl level between 18-23 wt % wereblended with either 3GO or 4G7 plasticizers and a mixture of alkali andalkaline earth metal salts for adhesion control and formed intosheeting. The PVB sheeting was then laminated and subjected to the edgepummel test. Results are given in Table 1. In Examples 1-18, theadhesion of the PVB sheeting to glass was within the necessary range forwindshield adhesion (1150-1800 N/cm²). Examples 19 and 20 describeformulations that yield acceptable edge pummel results but yieldwindshield adhesion significantly higher than acceptable for windshields(>3990 N/cm²). The ratio column describes the ratio (weight to weight)of potassium ions to magnesium ions added to the sheeting.

Comparative Example 1

The polyvinyl butyral interlayer used in this example was prepared byblending 38 parts tetraethyleneglycol diheptanoate (4G7) plasticizer perhundred parts of resin in an extruder. Magnesium formate was added asthe adhesion control agent. The resultant sheeting was laminated andtested by the edge pummel test. Results are given in Table 1. Despitethe acceptable edge pummel results, this laminate may possibly exhibitasymmetrical adhesion.

Comparative Example 2

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the plasticizer used wastriethyleneglycol di-2-ethylhexanoate (3GO) and the adhesion controlagent was magnesium 2-ethylbutyrate. Results of the edge pummel test aregiven in Table 1. Despite the acceptable edge pummel results, thislaminate may possibly exhibit asymmetrical adhesion.

Example 3

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the adhesion control agent wasa mixture of potassium formate and magnesium acetate where the potassiumto magnesium ratio was 2:1. Results of the edge pummel test are given inTable 1.

Example 4

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the plasticizer wastriethyleneglycol di-2-ethylhexanoate and the adhesion control agent wasa mixture of potassium formate and magnesium acetate where the potassiumto magnesium ratio was 3:1. Results of the edge pummel test are given inTable 1.

Example 5

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the adhesion control agent wasa mixture of potassium formate and magnesium acetate where the potassiumto magnesium ratio was 3:1. Results of the edge pummel test are given inTable 1.

Example 6

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the plasticizer was 3GO andthe adhesion control agent was a mixture of potassium formate andmagnesium 2-ethylbutyrate where the potassium to magnesium ratio was3:1. Results of the edge pummel test are given in Table 1.

Example 7

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the plasticizer was 3GO andthe adhesion control agent was a mixture of potassium acetate andmagnesium acetate where the potassium to magnesium ratio was 3:1.Results of the edge pummel test are given in Table 1.

Example 8

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the plasticizer was 3GO andthe adhesion control agent was a mixture of potassium acetate andmagnesium 2-ethylbutyrate where the potassium to magnesium ratio was3:1. Results of the edge pummel test are given in Table 1.

Example 9

The polyvinyl butyral interlayer of this example was prepared accordingto the procedure of Example 1 except that the adhesion control agent wasa mixture of potassium formate and magnesium acetate where the potassiumto magnesium ratio was 4:1. Results of the edge pummel test are given inTable 1.

Example 10

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the adhesion control agent was a mixture ofpotassium formate, potassium acetate, and magnesium acetate where thetotal potassium to magnesium ratio was 5:1. Results of the edge pummeltest are given in Table 1.

Example 11

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the plasticizer was triethyleneglycoldi-2-ethylhexanoate and the adhesion control agent was a mixture ofpotassium formate and magnesium 2-ethylbutyrate where the potassium tomagnesium ratio was 5:1. Results of the edge pummel test are given inTable 1.

Comparative Example 12

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the plasticizer was triethyleneglycoldi-2-ethylhexanoate and the adhesion control agent was a mixture ofpotassium acetate and magnesium acetate where the potassium to magnesiumratio was 7:1. Results of the edge pummel test are given in Table 1.

Comparative Example 13

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the adhesion control agent was a mixture ofpotassium formate and magnesium formate where the potassium to magnesiumratio was 10:1. Results of the edge pummel test are given in Table 1.

Comparative Example 14

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the adhesion control agent was a mixture ofpotassium formate and magnesium neodecanoate where the potassium tomagnesium ratio was 11:1. Results of the edge pummel test are given inTable 1.

Comparative Example 15

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the adhesion control agent was a mixture ofpotassium formate and magnesium 2-ethylhexanoate where the potassium tomagnesium ratio was 12:1. Results of the edge pummel test are given inTable 1.

Comparative Example 16

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the adhesion control agent was a mixture ofpotassium formate and magnesium sulfate where the potassium to magnesiumratio was 25:1. Results of the edge pummel test are given in Table 1.

Comparative Example 17

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the plasticizer was triethyleneglycoldi-2-ethylhexanoate and the adhesion control agent was a mixture ofpotassium formate and magnesium 2-ethylbutyrate where the potassium tomagnesium ratio was 25:1. Results of the edge pummel test are given inTable 1.

Comparative Example 18

The polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the adhesion control agent was a mixture ofpotassium formate and magnesium sulfate where the potassium to magnesiumratio was 105:1. Results of the edge pummel test are given in Table 1.

Comparative Example 19

They polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the plasticizer was triethyleneglycoldi-2-ethylhexanoate and the adhesion control agent was a mixture ofpotassium acetate and magnesium acetate where the potassium to magnesiumratio was 3:1. However, the interlayer of this example is not acceptablefor use in windshields since the adhesion levels was >1800 N/cm².

Comparative Example 20

They polyvinyl butyral interlayer of this example was prepared accordingto Example 1 except that the plasticizer was triethyleneglycoldi-2-ethylhexanoate and the adhesion control agent was a mixture ofpotassium acetate and magnesium acetate where the potassium to magnesiumratio was 3:1. However, the interlayer of this example is not acceptablefor use in windshields since the adhesion levels was >1800 N/cm².

TABLE 1 Ratio Salt Level, Bare (K:Mg) Potassium Salt Magnesium Salt ppm% Hydroxyl Plasticizer Vinyl, mm Example  3 2:1 Formate Acetate 429 224G7 0  4 3:1 Formate Acetate 504 18.5 3GO 0  5 3:1 Formate Acetate 50922 4G7 0  6 3:1 Formate 2-Ethyl butyrate 671 18.5 3GO 0  7 3:1 AcetateAcetate 559 18.5 3GO 0  8 3:1 Acetate 2-Ethyl butyrate 722 18.5 3GO 0  94:1 Formate Acetate 392 22 4G7 0 10 5:1 Formate/Acetate Acetate 498 224G7 0 11 5:1 Formate 2-Ethyl butyrate 551 18.5 3GO 0 ComparativeExamples  1 0:1 Formate 380 23 4G7 0  2 0:1 2-Ethyl butyrate 452 18.53GO 0 12 7:1 Acetate Acetate 451 18.5 3GO 5 13 10:1  Formate Formate 66023 4G7 9 14 11:1  Formate Neodecanoate 1162 23 4G7 10 15 12:1  Formate2-Ethyl hexanoate 1202 23 4G7 8 16 25:1  Formate Sulfate 470 22 4G7 11

1. A method for controlling adhesion of polyvinyl butyral to glass in aglass/polyvinyl butyral laminate comprising the step: mixing an adhesioncontrol agent with polyvinyl butyral and a plasticizer to obtain aplasticized polyvinyl butyral composition, wherein the adhesion controlagent comprises a mixture of potassium and magnesium salts in a ratiothat is in the range of from about 4:1 to about 5:1 (weight:weight,potassium:magnesium) and wherein the salts are included in aconcentration of up to about 1000 parts per million (ppm) based on thetotal weight of the plasticized polyvinyl butyral composition.
 2. Amethod for controlling adhesion of polyvinyl butyral to glass in aglass/polyvinyl butyral/glass laminate comprising the steps: a. mixingan adhesion control agent with polyvinyl butyral and a plasticizer toobtain a plasticized polyvinyl butyral composition, wherein the adhesioncontrol agent comprises a mixture of potassium and magnesium salts in aratio that is in the range of from about 4:1 to about 5:1(weight:weight, potassium:magnesium) and wherein the salts are includedin a concentration of up to about 1000 parts per million (ppm) based onthe total weight of the plasticized polyvinyl butyral composition; b.forming a sheet from the plasticized polyvinyl butyral composition; andc. laminating the sheet to glass sheets to form a glass/polyvinylbutyral/glass laminate.
 3. The method of claim 2 wherein the forming asheet comprises co-extruding the plasticized polyvinyl butyralcomposition at a temperature of about 175° C. to about 225° C.
 4. Themethod of claim 3 wherein the polyvinyl butyral has from about 17 wt %to about 23 wt % residual hydroxyl and the polyvinyl butyral compositioncontains the plasticizer in an amount of from about 30 to about 50 partsper hundred (pph) polyvinyl butyral.
 5. The process of claim 4 whereinthe salts are included in a total concentration of from about 200 toabout 1000 ppm.
 6. The process of claim 4 wherein the salts are includedin a total concentration of from about 300 to about 800 ppm.
 7. Theprocess of claim 5 wherein a. the magnesium salt is a carboxylate saltobtained from an acid selected from the group consisting of acetic acid,formic acid, citric acid, stearic acid, 2-ethyl hexanoic acid, 2-ethylbutyric acid, heptanoic acid, propanoic acid, pentanoic acid, hexanoicacid, heptanoic acid and lauric acid; b. the potassium salt is acarboxylate salt obtained from an acid selected from the groupconsisting of acetic acid, formic acid, citric acid, stearic acid,2-ethyl hexanoic acid, 2-ethyl butyric acid, heptanoic acid, propanoicacid, pentanoic acid, hexanoic acid, heptanoic acid, and lauric acid;and c. the plasticizer is selected from the group consisting of diestersobtained by the reaction of triethylene glycol or tetraethylene glycolwith aliphatic carboxylic acids having from 6 to 10 carbon atoms, anddiesters obtained from the reaction of sebacic acid with aliphaticalcohols having from 1 to 18 carbon atoms.
 8. The process of claim 7wherein the plasticizer is selected from the group consisting oftetraethylene glycol di(2-heptanoate) (4G7), triethylene glycoldi(2-ethylhexanoate) (3GO) or dibutyl sebacate (DBS).
 9. The process ofclaim 7 wherein the plasticizer is triethylene glycoldi(2-ethylhexanoate).
 10. The process of claim 7 wherein the plasticizeris triethylene glycol di(2-ethylhexanoate).
 11. The process of claim 7wherein the plasticizer is dibutyl sebacate (DBS).
 12. The process ofclaim 7 wherein the plasticizer is contained in an amount of about 30 toabout 45 pph polyvinyl butyral.
 13. The plasticized polyvinyl butyralcomposition of claim 7 wherein the plasticizer is contained in an amountof about 30 to about 40 pph polyvinyl butyral.
 14. The process of claim7 wherein the plasticizer is contained in an amount of about 32 to about45 pph polyvinyl butyral.
 15. The process of claim 12 wherein thepolyvinyl butyral has about 18 wt % to about 21 wt % residual hydroxyl.16. The process of claim 12 wherein the polyvinyl butyral has about 18.5wt % to about 19.5 wt % residual hydroxyl.
 17. The process of claim 2wherein the plasticized polyvinyl butyral composition contains about0.10 to about 0.70 pph by weight surfactants selected from the groupconsisting of sodium lauryl sulfate; ammonium lauryl sulfate; sodiumdioctyl sulfosuccinate; ammonium perfluorocarboxylates having from 6 to12 carbon atoms; sodium aryl sulfonates, adducts of chlorinatedcyclopentadiene and maleic anhydride; partially neutralizedpolymethacrylic acid; alkylaryl sulfonates; sodium N-oleyl-N-methyltaurate; sodium alkylaryl polyether sulfonates; triethanolamine laurylsulfate; diethyl dicyclohexyl ammonium lauryl sulfate; sodiumsecondary-alkyl sulfates; sulfated fatty acid esters; sulfated arylalcohols; and the like.
 18. The process of claim 14 wherein theplasticized polyvinyl butyral composition contains about 0.10 to about0.70 pph by weight of polyvinyl butyral of surfactant selected from thegroup consisting of sodium lauryl sulfate, sodium dioctylsulfosuccinate, sodium cocomethyl tauride, anddecyl(sulfophenoxy)benzenesulfonic acid disodium salt.
 19. The processof claim 2 wherein the plasticized polyvinyl butyral compositioncontains about 0.10 to about 0.70 pph by weight of polyvinyl butyral ofsodium dioctyl sulfosuccinates.
 20. A method for controlling adhesion ofpolyvinyl butyral to glass in a glass/polyvinyl butyral laminatecomprising the step: mixing an adhesion control agent with polyvinylbutyral and a tetraethylene glycol di(2-heptanoate) plasticizer toobtain a plasticized polyvinyl butyral composition, wherein the adhesioncontrol agent comprises a mixture of potassium and magnesium salts in aratio that is in the range of about 2:1 to about 5:1 (weight:weight,potassium:magnesium) and wherein the salts are included in aconcentration of up to about 1000 parts per million (ppm) based on thetotal weight of the plasticized polyvinyl butyral composition.
 21. Amethod for controlling adhesion of polyvinyl butyral to glass in aglass/polyvinyl butyral/glass laminate comprising the steps: a. mixingan adhesion control agent with polyvinyl butyral and a tetraethyleneglycol di(2-heptanoate) plasticizer to obtain a plasticized polyvinylbutyral composition, wherein the adhesion control agent comprises amixture of potassium and magnesium salts in a ratio that is in the rangeof about 2:1 to about 5:1 (weight:weight, potassium:magnesium) andwherein the salts are included in a concentration of up to about 1000parts per million (ppm) based on the total weight of the plasticizedpolyvinyl butyral composition; b. forming a sheet from the plasticizedpolyvinyl butyral composition; and c. laminating the sheet to glasssheets to form a glass/polyvinyl butyral/glass laminate.
 22. The methodof claim 21 wherein the adhesion of the laminate is in the range of fromabout 1000 N/cm² to about 1775 N/cm².
 23. The method of claim 21 whereinthe polyvinyl butyral has from about 17 wt % to about 23 wt % residualhydroxyl and the polyvinyl butyral composition contains the plasticizerin an amount of from about 30 to about 50 parts per hundred (pph)polyvinyl butyral.
 24. The process of claim 21 wherein the ratio is fromabout 3:1 to about 5:1.
 25. The process of claim 21 wherein the ratio isfrom about 4:1 to about 5:1 and the salts are included in a totalconcentration of from about 200 to about 1,000 ppm.